Weddell Seal AdaptationsLeptonychotes wedelli

How are Weddell seals adapted to survive in Antarctica?

The most southerly dwelling of all mammals they live at
the edge of pack ice wherever there is a breathing hole or tide
crack.

Anatomical - Structures of the body.

Behavioural - The manner in which animals
move and act.

Physiological - The internal functions
of the animal from biochemical, to cellular, tissue, organ
and whole organism levels.

Weddell
Seal Anatomical
Adaptations

Fore and hind limbs developed into flippers for swimming.

Smooth, streamlined shape to pass easily through the
water.

A substantial blubber layer lies under the skin acting
as insulation, so allowing the seals to swim indefinitely in
frigid Antarctic waters down to -2C that would incapacitate
a human in 10-15 mins and cause death in 60-90 ins (the coldest
that the sea gets, below this it freezes)

Large eyes to help hunting prey under water and frequently
under ice where light levels are very low.

Whiskers (vibrissae) that help the seals feel their
way in the dark when catching prey.

Weddell Seal Behavioural Adaptations

Weddell seals keep breathing holes in the ice open
by rasping back and forth with their teeth, this allows them
to live further south than any other mammal.

They can swim large distances between breathing holes
and cracks, finding the next hole using a form of sonar
with high pitched sounds.

They avoid the "bends" when diving by exhaling first
and allowing the lungs and air passages to collapse so there
is no contained air that will allow nitrogen to dissolve in
the blood and cause the bends.

Males compete for underwater territories around a breathing
hole which gives access to females using the same breathing
hole

They flush fish out that are hiding in broken up ice by blowing
bubbles.

Weddell
Seal Physiological
Adaptations

Weddell seals can dive for over an hour, though 20
minute dives are more common, they can dive to 600m.

The metabolic "cost" of diving in terms of extra oxygen consumption
is about 1.5 x the resting rate - this is much lower
than other diving seals and birds and makes diving more efficient.

The blood has high haemoglobin concentrations and can
carry 1.6 times more oxygen than the same volume of human blood
which allows for longer and more energetic dives.

Weddell seal milk is one of the richest produced by
any mammal, containing about 60% fat so allowing rapid
growth and development of the young during the short Antarctic
summer so they are big and strong enough to face the winter.

The females mate shortly after giving birth, the embryo
goes into a kind of hibernation for a few months before it starts
to develop and can be born at the correct time of year. This
happens as males and females do not come into regular contact
at other times of year.